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2 years ago

How many valence electrons are there in Se atom?

Chemistry

2 answers:

a_sh-v [17]2 years ago

7 0

Answer:

The numer of valence electrons is defined as the number of electrons present in the outer most shell of the atom.So, in the case if selenium, there are 6.

Lena [83]2 years ago

5 0

Answer:

4 valence electrons

Despite the fact that the word silicon has a ubiquitous affiliation with all things electronic, Si itself is not a good electrical conductor. It has 4 valence electrons, meaning that filling its outer shell it can form a very strong lattice with 4 neighboring Si atoms-with no un-bonded electrons remaining

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How long does it take electrons to get from the car battery to the starting motor? Assume the current is 137 A and the electrons

WARRIOR [948]

Answer:

t = 55.79 min

Explanation:

First, the problem is asking for calculate the time that it takes electrons from the battery to the motor.

The general formula to calculate time is:

t = d/V (1)

Where:

d: distance or length

V: speed

Now, we don't have data of speed, but we can know an expression of current density in function of the distance which is the following:

J = n*q*V (2)

Where:

q: charge of the particle (1.6x10^-19 C)

n: number of charge carriers per unit of volume

Current density (J) is actually current per Area so:

J = I/A (3)

Replacing (3) in (2) we have:

I/A = nqV

Solving for V:

V = I/Anq (4)

Finally, if we replace this expression in (1) we have:

t = nqAd / I (5)

Now, the value of n, it's not given but it can be calculated because we have mass density, molar mass and avogadro's number, so this value of "n" can be calculated using the following expression:

n = D * Av / MM (6)

Where:

D: mass density (kg/m³)

Av: avogadro number (6.02x10^23 atom/mol)

MM: molar mass (kg/mol)

Putting the data that we know to calculate n we have:

n = 8960 * 6.02x10^23 / 0.0635

n = 8.49x10^28 atom/m³

Now with the value of n, we can finally calculate the time:

t = nqAd / I

A is the area and it should be in m²: 44.6 mm² / 1x10^6 m = 4.46x10^-5 m²

d is the length in meter: 75.7 cm / 100 cm/m = 0.757 m

so replacing these data in (5):

t = 8.49x10^28 * 1.6x10^-19 * 4.46x10^-5 * 0.757 / 137

t = 3,347.63 s

But the answer is in minute so:

t = 3,347.63 / 60

t = 55.79 min

so the electrons takes 56 min aprox. to go from the car battery to the starting motor.

4 0

2 years ago

What does absolute zero physically mean at the particle level? ASAP!

antoniya [11.8K]

Answer:

Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin.

7 0

1 year ago

A. How many protons, electrons, and neutrons make up an atom

mestny [16]

Answer:

45 neutrons

Explanation:

Bromine has 35 protons and a mass number of 80. a) How many neutrons does the atom of bromine have? The mass number = protons + neutrons. Bromine has a mass number of 80 and 35 protons so 80-35 = 45 neutrons.

5 0

1 year ago

Sulfur and oxygen form both sulfur dioxide and sulfur trioxide. When samples of these are decomposed, the sulfur dioxide produce

Diano4ka-milaya [45]

To determine the mass of oxygen per gram of sulfur for sulfur dioxide, we simply obtain the ratio of the mass of oxygen and the mass of sulfur produced from the decomposition of sulfur dioxide. All other values given in the problem statement above are just to confuse us that the question is a difficult one. We do as follows:

mass of oxygen per gram sulfur = 3.45 g / 3.46 g
mass of oxygen per gram sulfur = 0.9971 g O2 / g S

4 0

2 years ago

A laser produces red light of wavelength 632.8 nm. Calculate the energy,

Ira Lisetskai [31]

Answer:

189.2 KJ

Explanation:

Data Given

wavelength of the light = 632.8 nm

Convert nm to m

1 nm = 1 x 10⁻⁹

632.8 nm = 632.8 x 1 x 10⁻⁹ = 6.328 x 10⁻⁷m

Energy of 1 mole of photon = ?

Solution

Formula used

E = hc/λ

where

E = energy of photon

h = Planck's Constant

Planck's Constant = 6.626 x 10⁻³⁴ Js

c = speed of light

speed of light = 3 × 10⁸ ms⁻¹

λ = wavelength of light

Put values in above equation

E = hc/λ

E = 6.626 x 10⁻³⁴ Js ( 3 × 10⁸ ms⁻¹ / 6.328 x 10⁻⁷m)

E = 6.626 x 10⁻³⁴ Js (4.741 x 10¹⁴s⁻¹)

E = 3.141 x 10⁻¹⁹J

3.141 x 10⁻¹⁹J is energy for one photon

Now we have to find energy of 1 mole of photon

As we know that

1 mole consists of 6.022 x10²³ numbers of photons

So,

Energy for one mole photons = 3.141 x 10⁻¹⁹J x 6.022 x10²³

Energy for one mole photons = 1.89 x 10⁵ J

Now convert J to KJ

1000 J = 1 KJ

1.89 x 10⁵ J = 1.89 x 10⁵ /1000 = 189.2 KJ

So,

energy of one mole of photons = 189.2 KJ

3 0

2 years ago